Fix regression test output due to upstream changes

Recently Postgres updated time zone data files to tzdata2024b:
* 17.1: postgres/postgres@cad65907ee
* 16.5: postgres/postgres@a0c8d600bb
* 15.9: postgres/postgres@74f70cb8633
* 14.14: postgres/postgres@dedced73e00

In #7276 we forced our regression tests to explicit use PST8PDT
timezone but for some reason on tzdata2024b it definition changed.
The change is valid for dates before 1970 and this is exactly the
case here for the CAgg watermark test outputs.

We're also noticing consistently failures in our CI:
* https://github.com/timescale/timescaledb/actions/runs/11883366631/job/33110029493#step:20:35
* https://github.com/timescale/timescaledb/actions/runs/11883366631/job/33110029375#step:20:35

Fixed it by using the timezone `UTC-8` instead to keep compatibility
with all calculations in the regression suite. The only noticible
change is timezone output information.

tsl/test/expected/cagg_ddl-14.out

@@ -22,7 +22,7 @@ SELECT table_name FROM create_hypertable('conditions', 'timec');
 
 -- schema tests
 \c :TEST_DBNAME :ROLE_CLUSTER_SUPERUSER
-SET timezone TO PST8PDT;
+SET timezone TO 'UTC+8';
 -- drop if the tablespace1 and/or tablespace2 exists
 SET client_min_messages TO error;
 DROP TABLESPACE IF EXISTS tablespace1;
@@ -480,11 +480,11 @@ CALL refresh_continuous_aggregate('cagg_expr', NULL, NULL);
 SELECT * FROM cagg_expr ORDER BY time LIMIT 5;
              time             | const | numeric |                    first                     | case | coalesce | avg1 | avg2 
 ------------------------------+-------+---------+----------------------------------------------+------+----------+------+------
- Fri Dec 31 16:00:00 1999 PST | Const |     4.3 | ("Sat Jan 01 00:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Sat Jan 01 16:00:00 2000 PST | Const |     4.3 | ("Sat Jan 01 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Sun Jan 02 16:00:00 2000 PST | Const |     4.3 | ("Sun Jan 02 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Mon Jan 03 16:00:00 2000 PST | Const |     4.3 | ("Mon Jan 03 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Tue Jan 04 16:00:00 2000 PST | Const |     4.3 | ("Tue Jan 04 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Fri Dec 31 16:00:00 1999 UTC | Const |     4.3 | ("Sat Jan 01 00:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Sat Jan 01 16:00:00 2000 UTC | Const |     4.3 | ("Sat Jan 01 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Sun Jan 02 16:00:00 2000 UTC | Const |     4.3 | ("Sun Jan 02 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Mon Jan 03 16:00:00 2000 UTC | Const |     4.3 | ("Mon Jan 03 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Tue Jan 04 16:00:00 2000 UTC | Const |     4.3 | ("Tue Jan 04 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
 (5 rows)
 
 --test materialization of invalidation before drop
@@ -1808,12 +1808,12 @@ View definition:
 SELECT * FROM cashflows ORDER BY cashflows;
             bucket            | amount | cashflow | cashflow2 
 ------------------------------+--------+----------+-----------
- Sun Dec 31 16:00:00 2017 PST |      1 |       10 |        11
- Mon Jan 01 16:00:00 2018 PST |     -1 |      -30 |        29
- Wed Oct 31 17:00:00 2018 PDT |     -1 |      -20 |        19
- Wed Oct 31 17:00:00 2018 PDT |      1 |       30 |        31
- Thu Nov 01 17:00:00 2018 PDT |     -1 |      -10 |         9
- Thu Nov 01 17:00:00 2018 PDT |      1 |       10 |        11
+ Sun Dec 31 16:00:00 2017 UTC |      1 |       10 |        11
+ Mon Jan 01 16:00:00 2018 UTC |     -1 |      -30 |        29
+ Wed Oct 31 16:00:00 2018 UTC |     -1 |      -20 |        19
+ Wed Oct 31 16:00:00 2018 UTC |      1 |       30 |        31
+ Thu Nov 01 16:00:00 2018 UTC |     -1 |      -10 |         9
+ Thu Nov 01 16:00:00 2018 UTC |      1 |       10 |        11
 (6 rows)
 
 -- test cagg creation with named arguments in time_bucket
@@ -1868,8 +1868,8 @@ CALL refresh_continuous_aggregate('transactions_montly', NULL, INTERVAL '1 month
 SELECT * FROM transactions_montly ORDER BY bucket;
             bucket            | sum | max | min 
 ------------------------------+-----+-----+-----
- Sun Dec 31 16:00:00 2017 PST |  40 |  10 |  10
- Wed Oct 31 17:00:00 2018 PDT |  70 |  10 |  10
+ Sun Dec 31 16:00:00 2017 UTC |  40 |  10 |  10
+ Wed Oct 31 16:00:00 2018 UTC |  70 |  10 |  10
 (2 rows)
 
 TRUNCATE transactions_montly;
@@ -1878,16 +1878,16 @@ CALL refresh_continuous_aggregate('transactions_montly', NULL, '2018-11-01 11:50
 SELECT * FROM transactions_montly ORDER BY bucket;
             bucket            | sum | max | min 
 ------------------------------+-----+-----+-----
- Sun Dec 31 16:00:00 2017 PST |  40 |  10 |  10
+ Sun Dec 31 16:00:00 2017 UTC |  40 |  10 |  10
 (1 row)
 
 -- Full refresh the CAGG
 CALL refresh_continuous_aggregate('transactions_montly', NULL, NULL);
 SELECT * FROM transactions_montly ORDER BY bucket;
             bucket            | sum | max | min 
 ------------------------------+-----+-----+-----
- Sun Dec 31 16:00:00 2017 PST |  40 |  10 |  10
- Wed Oct 31 17:00:00 2018 PDT |  70 |  10 |  10
+ Sun Dec 31 16:00:00 2017 UTC |  40 |  10 |  10
+ Wed Oct 31 16:00:00 2018 UTC |  70 |  10 |  10
 (2 rows)
 
 -- Check set_chunk_time_interval on continuous aggregate
@@ -1995,12 +1995,12 @@ UNION ALL
 SELECT * FROM conditions_daily ORDER BY bucket, location;
  location |            bucket            | avg 
 ----------+------------------------------+-----
- SFO      | Sun Dec 31 16:00:00 2017 PST |  55
- NYC      | Mon Jan 01 16:00:00 2018 PST |  65
- POR      | Mon Jan 01 16:00:00 2018 PST | 100
- SFO      | Mon Jan 01 16:00:00 2018 PST |  65
- NYC      | Wed Oct 31 17:00:00 2018 PDT |  65
- NYC      | Thu Nov 01 17:00:00 2018 PDT |  15
+ SFO      | Sun Dec 31 16:00:00 2017 UTC |  55
+ NYC      | Mon Jan 01 16:00:00 2018 UTC |  65
+ POR      | Mon Jan 01 16:00:00 2018 UTC | 100
+ SFO      | Mon Jan 01 16:00:00 2018 UTC |  65
+ NYC      | Wed Oct 31 16:00:00 2018 UTC |  65
+ NYC      | Thu Nov 01 16:00:00 2018 UTC |  15
 (6 rows)
 
 -- Should return ROWS because we refreshed it
@@ -2022,12 +2022,12 @@ CALL refresh_continuous_aggregate('conditions_daily', NULL, NULL);
 SELECT * FROM conditions_daily ORDER BY bucket, location;
  location |            bucket            | avg 
 ----------+------------------------------+-----
- SFO      | Sun Dec 31 16:00:00 2017 PST |  55
- NYC      | Mon Jan 01 16:00:00 2018 PST |  65
- POR      | Mon Jan 01 16:00:00 2018 PST | 100
- SFO      | Mon Jan 01 16:00:00 2018 PST |  65
- NYC      | Wed Oct 31 17:00:00 2018 PDT |  65
- NYC      | Thu Nov 01 17:00:00 2018 PDT |  15
+ SFO      | Sun Dec 31 16:00:00 2017 UTC |  55
+ NYC      | Mon Jan 01 16:00:00 2018 UTC |  65
+ POR      | Mon Jan 01 16:00:00 2018 UTC | 100
+ SFO      | Mon Jan 01 16:00:00 2018 UTC |  65
+ NYC      | Wed Oct 31 16:00:00 2018 UTC |  65
+ NYC      | Thu Nov 01 16:00:00 2018 UTC |  15
 (6 rows)
 
 -- Test TRUNCATE over a Realtime CAgg
@@ -2046,7 +2046,7 @@ SELECT mat_hypertable_id FROM _timescaledb_catalog.continuous_agg WHERE user_vie
 SELECT _timescaledb_functions.to_timestamp(_timescaledb_functions.cagg_watermark(:mat_hypertable_id)) AS watermak_empty_cagg;
        watermak_empty_cagg       
 ---------------------------------
- Sun Nov 23 16:00:00 4714 PST BC
+ Sun Nov 23 16:00:00 4714 UTC BC
 (1 row)
 
 -- Refresh the CAGG
@@ -2055,7 +2055,7 @@ CALL refresh_continuous_aggregate('conditions_daily', NULL, NULL);
 SELECT _timescaledb_functions.to_timestamp(_timescaledb_functions.cagg_watermark(:mat_hypertable_id)) AS watermak_before;
        watermak_before        
 ------------------------------
- Fri Nov 02 17:00:00 2018 PDT
+ Fri Nov 02 16:00:00 2018 UTC
 (1 row)
 
 -- Exists chunks before truncate the cagg (> 0)
@@ -2078,19 +2078,19 @@ SELECT count(*) FROM show_chunks('conditions_daily');
 SELECT _timescaledb_functions.to_timestamp(_timescaledb_functions.cagg_watermark(:mat_hypertable_id)) AS watermak_after;
          watermak_after          
 ---------------------------------
- Sun Nov 23 16:00:00 4714 PST BC
+ Sun Nov 23 16:00:00 4714 UTC BC
 (1 row)
 
 -- Should return ROWS because the watermark was reseted by the TRUNCATE
 SELECT * FROM conditions_daily ORDER BY bucket, location;
  location |            bucket            | avg 
 ----------+------------------------------+-----
- SFO      | Sun Dec 31 16:00:00 2017 PST |  55
- NYC      | Mon Jan 01 16:00:00 2018 PST |  65
- POR      | Mon Jan 01 16:00:00 2018 PST | 100
- SFO      | Mon Jan 01 16:00:00 2018 PST |  65
- NYC      | Wed Oct 31 17:00:00 2018 PDT |  65
- NYC      | Thu Nov 01 17:00:00 2018 PDT |  15
+ SFO      | Sun Dec 31 16:00:00 2017 UTC |  55
+ NYC      | Mon Jan 01 16:00:00 2018 UTC |  65
+ POR      | Mon Jan 01 16:00:00 2018 UTC | 100
+ SFO      | Mon Jan 01 16:00:00 2018 UTC |  65
+ NYC      | Wed Oct 31 16:00:00 2018 UTC |  65
+ NYC      | Thu Nov 01 16:00:00 2018 UTC |  15
 (6 rows)
 
 -- check compression settings are cleaned up when deleting a cagg with compression

tsl/test/expected/cagg_ddl-15.out

@@ -22,7 +22,7 @@ SELECT table_name FROM create_hypertable('conditions', 'timec');
 
 -- schema tests
 \c :TEST_DBNAME :ROLE_CLUSTER_SUPERUSER
-SET timezone TO PST8PDT;
+SET timezone TO 'UTC+8';
 -- drop if the tablespace1 and/or tablespace2 exists
 SET client_min_messages TO error;
 DROP TABLESPACE IF EXISTS tablespace1;
@@ -480,11 +480,11 @@ CALL refresh_continuous_aggregate('cagg_expr', NULL, NULL);
 SELECT * FROM cagg_expr ORDER BY time LIMIT 5;
              time             | const | numeric |                    first                     | case | coalesce | avg1 | avg2 
 ------------------------------+-------+---------+----------------------------------------------+------+----------+------+------
- Fri Dec 31 16:00:00 1999 PST | Const |     4.3 | ("Sat Jan 01 00:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Sat Jan 01 16:00:00 2000 PST | Const |     4.3 | ("Sat Jan 01 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Sun Jan 02 16:00:00 2000 PST | Const |     4.3 | ("Sun Jan 02 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Mon Jan 03 16:00:00 2000 PST | Const |     4.3 | ("Mon Jan 03 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
- Tue Jan 04 16:00:00 2000 PST | Const |     4.3 | ("Tue Jan 04 16:00:00 2000 PST",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Fri Dec 31 16:00:00 1999 UTC | Const |     4.3 | ("Sat Jan 01 00:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Sat Jan 01 16:00:00 2000 UTC | Const |     4.3 | ("Sat Jan 01 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Sun Jan 02 16:00:00 2000 UTC | Const |     4.3 | ("Sun Jan 02 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Mon Jan 03 16:00:00 2000 UTC | Const |     4.3 | ("Mon Jan 03 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
+ Tue Jan 04 16:00:00 2000 UTC | Const |     4.3 | ("Tue Jan 04 16:00:00 2000 UTC",1,0.25,0.75) | foo  | coalesce |    1 |    1
 (5 rows)
 
 --test materialization of invalidation before drop
@@ -1808,12 +1808,12 @@ View definition:
 SELECT * FROM cashflows ORDER BY cashflows;
             bucket            | amount | cashflow | cashflow2 
 ------------------------------+--------+----------+-----------
- Sun Dec 31 16:00:00 2017 PST |      1 |       10 |        11
- Mon Jan 01 16:00:00 2018 PST |     -1 |      -30 |        29
- Wed Oct 31 17:00:00 2018 PDT |     -1 |      -20 |        19
- Wed Oct 31 17:00:00 2018 PDT |      1 |       30 |        31
- Thu Nov 01 17:00:00 2018 PDT |     -1 |      -10 |         9
- Thu Nov 01 17:00:00 2018 PDT |      1 |       10 |        11
+ Sun Dec 31 16:00:00 2017 UTC |      1 |       10 |        11
+ Mon Jan 01 16:00:00 2018 UTC |     -1 |      -30 |        29
+ Wed Oct 31 16:00:00 2018 UTC |     -1 |      -20 |        19
+ Wed Oct 31 16:00:00 2018 UTC |      1 |       30 |        31
+ Thu Nov 01 16:00:00 2018 UTC |     -1 |      -10 |         9
+ Thu Nov 01 16:00:00 2018 UTC |      1 |       10 |        11
 (6 rows)
 
 -- test cagg creation with named arguments in time_bucket
@@ -1868,8 +1868,8 @@ CALL refresh_continuous_aggregate('transactions_montly', NULL, INTERVAL '1 month
 SELECT * FROM transactions_montly ORDER BY bucket;
             bucket            | sum | max | min 
 ------------------------------+-----+-----+-----
- Sun Dec 31 16:00:00 2017 PST |  40 |  10 |  10
- Wed Oct 31 17:00:00 2018 PDT |  70 |  10 |  10
+ Sun Dec 31 16:00:00 2017 UTC |  40 |  10 |  10
+ Wed Oct 31 16:00:00 2018 UTC |  70 |  10 |  10
 (2 rows)
 
 TRUNCATE transactions_montly;
@@ -1878,16 +1878,16 @@ CALL refresh_continuous_aggregate('transactions_montly', NULL, '2018-11-01 11:50
 SELECT * FROM transactions_montly ORDER BY bucket;
             bucket            | sum | max | min 
 ------------------------------+-----+-----+-----
- Sun Dec 31 16:00:00 2017 PST |  40 |  10 |  10
+ Sun Dec 31 16:00:00 2017 UTC |  40 |  10 |  10
 (1 row)
 
 -- Full refresh the CAGG
 CALL refresh_continuous_aggregate('transactions_montly', NULL, NULL);
 SELECT * FROM transactions_montly ORDER BY bucket;
             bucket            | sum | max | min 
 ------------------------------+-----+-----+-----
- Sun Dec 31 16:00:00 2017 PST |  40 |  10 |  10
- Wed Oct 31 17:00:00 2018 PDT |  70 |  10 |  10
+ Sun Dec 31 16:00:00 2017 UTC |  40 |  10 |  10
+ Wed Oct 31 16:00:00 2018 UTC |  70 |  10 |  10
 (2 rows)
 
 -- Check set_chunk_time_interval on continuous aggregate
@@ -1995,12 +1995,12 @@ UNION ALL
 SELECT * FROM conditions_daily ORDER BY bucket, location;
  location |            bucket            | avg 
 ----------+------------------------------+-----
- SFO      | Sun Dec 31 16:00:00 2017 PST |  55
- NYC      | Mon Jan 01 16:00:00 2018 PST |  65
- POR      | Mon Jan 01 16:00:00 2018 PST | 100
- SFO      | Mon Jan 01 16:00:00 2018 PST |  65
- NYC      | Wed Oct 31 17:00:00 2018 PDT |  65
- NYC      | Thu Nov 01 17:00:00 2018 PDT |  15
+ SFO      | Sun Dec 31 16:00:00 2017 UTC |  55
+ NYC      | Mon Jan 01 16:00:00 2018 UTC |  65
+ POR      | Mon Jan 01 16:00:00 2018 UTC | 100
+ SFO      | Mon Jan 01 16:00:00 2018 UTC |  65
+ NYC      | Wed Oct 31 16:00:00 2018 UTC |  65
+ NYC      | Thu Nov 01 16:00:00 2018 UTC |  15
 (6 rows)
 
 -- Should return ROWS because we refreshed it
@@ -2022,12 +2022,12 @@ CALL refresh_continuous_aggregate('conditions_daily', NULL, NULL);
 SELECT * FROM conditions_daily ORDER BY bucket, location;
  location |            bucket            | avg 
 ----------+------------------------------+-----
- SFO      | Sun Dec 31 16:00:00 2017 PST |  55
- NYC      | Mon Jan 01 16:00:00 2018 PST |  65
- POR      | Mon Jan 01 16:00:00 2018 PST | 100
- SFO      | Mon Jan 01 16:00:00 2018 PST |  65
- NYC      | Wed Oct 31 17:00:00 2018 PDT |  65
- NYC      | Thu Nov 01 17:00:00 2018 PDT |  15
+ SFO      | Sun Dec 31 16:00:00 2017 UTC |  55
+ NYC      | Mon Jan 01 16:00:00 2018 UTC |  65
+ POR      | Mon Jan 01 16:00:00 2018 UTC | 100
+ SFO      | Mon Jan 01 16:00:00 2018 UTC |  65
+ NYC      | Wed Oct 31 16:00:00 2018 UTC |  65
+ NYC      | Thu Nov 01 16:00:00 2018 UTC |  15
 (6 rows)
 
 -- Test TRUNCATE over a Realtime CAgg
@@ -2046,7 +2046,7 @@ SELECT mat_hypertable_id FROM _timescaledb_catalog.continuous_agg WHERE user_vie
 SELECT _timescaledb_functions.to_timestamp(_timescaledb_functions.cagg_watermark(:mat_hypertable_id)) AS watermak_empty_cagg;
        watermak_empty_cagg       
 ---------------------------------
- Sun Nov 23 16:00:00 4714 PST BC
+ Sun Nov 23 16:00:00 4714 UTC BC
 (1 row)
 
 -- Refresh the CAGG
@@ -2055,7 +2055,7 @@ CALL refresh_continuous_aggregate('conditions_daily', NULL, NULL);
 SELECT _timescaledb_functions.to_timestamp(_timescaledb_functions.cagg_watermark(:mat_hypertable_id)) AS watermak_before;
        watermak_before        
 ------------------------------
- Fri Nov 02 17:00:00 2018 PDT
+ Fri Nov 02 16:00:00 2018 UTC
 (1 row)
 
 -- Exists chunks before truncate the cagg (> 0)
@@ -2078,19 +2078,19 @@ SELECT count(*) FROM show_chunks('conditions_daily');
 SELECT _timescaledb_functions.to_timestamp(_timescaledb_functions.cagg_watermark(:mat_hypertable_id)) AS watermak_after;
          watermak_after          
 ---------------------------------
- Sun Nov 23 16:00:00 4714 PST BC
+ Sun Nov 23 16:00:00 4714 UTC BC
 (1 row)
 
 -- Should return ROWS because the watermark was reseted by the TRUNCATE
 SELECT * FROM conditions_daily ORDER BY bucket, location;
  location |            bucket            | avg 
 ----------+------------------------------+-----
- SFO      | Sun Dec 31 16:00:00 2017 PST |  55
- NYC      | Mon Jan 01 16:00:00 2018 PST |  65
- POR      | Mon Jan 01 16:00:00 2018 PST | 100
- SFO      | Mon Jan 01 16:00:00 2018 PST |  65
- NYC      | Wed Oct 31 17:00:00 2018 PDT |  65
- NYC      | Thu Nov 01 17:00:00 2018 PDT |  15
+ SFO      | Sun Dec 31 16:00:00 2017 UTC |  55
+ NYC      | Mon Jan 01 16:00:00 2018 UTC |  65
+ POR      | Mon Jan 01 16:00:00 2018 UTC | 100
+ SFO      | Mon Jan 01 16:00:00 2018 UTC |  65
+ NYC      | Wed Oct 31 16:00:00 2018 UTC |  65
+ NYC      | Thu Nov 01 16:00:00 2018 UTC |  15
 (6 rows)
 
 -- check compression settings are cleaned up when deleting a cagg with compression